Vertebrate mothers deposit variable amounts of maternal steroid hormones in their eggs. Early exposure to steroids, whether endogenous or exogenous, may have long-lasting effects on the development and survival of an organism. In avian species, the concentration of these steroids, mostly androgens, found in the egg yolks vary within and among clutches. The possibility of organizational actions of these naturally occurring doses of maternal androgens, analogous to that regulating development of sexually dimorphic traits and behavior, remains largely unexplored. Because the offspring develop outside the mother, birds provide an excellent model system in which to manipulate and examine maternal hormonal effects without potential feedback effects derived from maternal endocrine physiology. The avian model of early hormone effects thus represents a very promising alternative system to the well-established mammalian model. It is the specific goal of the following proposed study to provide information regarding long-term maternal hormone effects on offspring development including potential transgenerational effects. Using an experimental design, exposure to testosterone and anti-androgens during development will be manipulated in order to examine the effects on morphology, physiology, and behavior of juvenile and adult offspring. New information will be obtained regarding 1) the effects of prenatal testosterone and anti-androgen treatment on offspring growth and development; 2) the organizational effects of testosterone and antiandrogens on offspring reproduction and parental behavior; and 3) the plasticity of maternal hormonal effects on subsequent generations. Results from these studies will contribute to our knowledge of how early hormone exposure (or absence) influence and organize the brain for later occurring activational events. With the growing popularity of hormonal treatments in various clinical populations and the prevalence of environmental anti-androgens, it is critical to not only understand how early hormonal histories influences an individual's current physiology and behavior but also how it might influence the phenotype of their future offspring via transgenerational maternal effects.